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Read and share online: https://www.fsf.org/blogs/community/gpl-compliant-legal-notices-author-attributions.

Notices accompanying free software, like clear authorship and license information, can serve an important purpose when they communicate to users the freedom to run, study, modify, copy, and distribute free software. However, requirements to preserve notices could conflict with user freedom. The GNU General Public License (GPL) includes a set of rules protecting notices while also ensuring that users have full software freedom. For example, legal notices cannot be used to restrict distribution of the program, or its modification. Users have some flexibility in changing how the program handles notices.

Software freedom gains strength through complete and good licensing practices, including informing users of their rights, as it helps license enforcement in case of a violation. Making sure that the authorship and license information gets to users is also highly desired for the program’s hard working free software developers, as it provides the developers with the recognition they deserve. Thus, the obligation to preserve legal notices provided was deliberately drafted into the GNU GPL with the intention to ensure it cannot be abused to limit software freedom (the exact wording is different between the GNU GPLv2 and the GNU GPLv3).

Clear authorship and license information notices are a must for users who want to make sure they are using free software, know what their exact scope of rights are, and who granted them. Providing this information is critical to software freedom, which is why the Free Software Foundation (FSF) recommends including the notices in the headers of all source code files, and making interactive programs output these notices. So, for example, when a program accepts user commands and presents outputs using the computer screen, the FSF recommends the program display a brief notice about copyright and copying permissions when it starts up.

Every now and then, the FSF's Licensing and Compliance Lab receives questions about how the GPL's clauses on notices are intended to apply in the context of web applications. The specific clauses that are being referred to in GPLv2 is Sec. 2(c) and in GPLv3 are Sec. 5(d) and Sec. 7(b). A practical example is that a website operator could want to remove the attribution from a page generated with the application, or someone could disagree with a website operator for having removed such attribution. Some developers ask if it is okay to require that people modifying the software retain links or logos as a condition to the license. Our answer could be generalized to say that both the GNU GPLv2 and GPLv3 are intended to protect certain user interface notices in certain situations. This does not cover just any notice, and the protection of notices is not absolute.

Different versions of the GPL on the topic

The GNU GPLv2 Sec. 2(c) requires people who modify the interactive program released under that license to cause it to print or display legal notices, but they can change where and how it displays those notices, as long as it does so in some form or another. The license also includes the following exception:

"if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement".

The GNU GPLv3 intends to handle notices in a similar way. It introduces the term "Appropriate Legal Notices" (ALNs), which are notices displayed in an interactive user interface that include the copyright notice. Please note that "copyright notice" is a notice that contains: the word copyright (or the (C) symbol), the year of first publication of the work, and the name of the copyright holder. Any other information is not part of a copyright notice. ALNs may also include information that:

"tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License."

The GNU GPLv3 goes on to introduce a condition on the right to convey in Sec. 5(d), which is equivalent to the GNU GPLv2 Sec. 2(c):

"If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so."

Similar to the GPLv2, the GPLv3 requirement only applies to the extent that any ALNs exist and are displayed in the original version.

The GNU GPLv3 then goes on to specifically allow people to require preservation of "specified reasonable legal notices or author attributions" in the ALNs (Sec. 7(b)). We explained the intent of this section in footnote 14 of the "GPLv3 Final Discussion Draft Rationale," stating:

"We have broadened the clause slightly to also permit terms that require preservation of such notices in the Appropriate Legal Notices displayed by interactive user interfaces that comply with the requirements of subsection 5d."

In summary, people who modify programs released under the GNU GPLs can still change where and how an interactive program displays those notices. For example, if the original program put these notices at the bottom of every page, someone modifying the software could conceivably remove those and have them appear only on a single "About this software" page.

GPL-compatible requirements of legal notices and author attributions

Asking people modifying the software to retain other information, such as a link or logo is fine as a request, but it cannot be added as a requirement on top of the GNU GPLv2 under its clauses covering copyright and license notices.

The GNU GPLv3 Sec. 7(b) does make it possible to extend the requirement, but only to cover items that can be deemed as "reasonable legal notices or author attributions." The terms "legal notice" and "author attribution" cannot be stretched to cover completely different items. "Legal notice" normally means a notice advising a person of their rights or obligations. "Author attribution" is an identification of the natural person who is the author of the copyrighted work. This means that, for example, links leading to different materials are not intended to benefit from Sec. 7(b). Apart from some specific situations, logos are neither "legal notices" nor "author attributions" as normally understood.

While we are open to considering arguments that some specific items could fall within either of the terms, we believe it is necessary to evaluate how a given requirement to preserve an item aligns with the intention of the GNU GPL. It has never been the intention of the GNU GPL to make it hard or impossible for users to run, modify, or distribute programs under the GNU GPL.

Requirements to preserve notices that conflict with the intention of the GPL

An additional term requiring that users preserve notices may conflict with the said intent of the GNU GPL, for example, when it is drafted in such a way that the user cannot both distribute the program (including a work based on the program) and satisfy the requirement placed upon them by the notice.

Consider a term similar to the infamous "advertising clause" of the Original BSD license, which said that every advertisement mentioning the software must include a particular sentence. A project combining a program licensed under such a term with other programs, especially those licensed under similar terms, would have the obligation to preserve a plethora of different notices. Satisfying this requirement would be difficult to say the least, and sometimes is simply not possible if the program is to remain usable. The Original BSD license was deemed GPL-incompatible because of this clause. In fact, in the 1990s, FSF founder Richard M. Stallman convinced the dean at the University of California in charge of the BSD project to change the license on BSD releases to eliminate that clause, which led to the disappearance of the Original BSD license.

For another example, an additional term requiring preserving an attribution verbatim, even if the program was modified or combined with other programs, could put users in legal jeopardy. By preserving the attribution, one may face licensors' claims for misattributing something to them that they did not write. By modifying or removing the attribution so that it does not confuse users about who wrote what, they may face licensors' claims for not following the additional term.

Attribution through links or logos consistent with GNU GPLv3 Sec. 7(e)

The GNU GPLv3 Sec. 7(e) should rather be used if a licensor's goal is to preserve — to some extent — links or logos in the program's interface. This section acknowledges that the licensor can decline,

"to grant rights under trademark law for use of some trade names, trademarks, or service marks."

Putting trademarked links or logos in the program's interface and explicitly declining a trademark license thus gives the trademark holder a way to stop uses harmful to their reputation, balanced by the users' option to remove the trademarks in order to distribute modifications freely. That way of securing attribution (or even advertising) benefit is consistent with the GNU GPLv3's intent to protect software freedom. People who modify the software still have some flexibility to decide how notices included in ALNs are displayed in their software, and other developers cannot use Sec. 7 to try to take that flexibility away.

Sincerely,

Krzysztof Siewicz
Licensing and compliance manager